MgrB Inactivation Is Responsible for Acquired Resistance to Colistin in Enterobacter hormaechei subsp. steigerwaltii

Multidrug-resistant strains belonging to the Enterobacter cloacae complex (ECC) group, and especially those belonging to clusters C-III, C-IV, and C-VIII, have increasingly emerged as a leading cause of health care-associated infections, with colistin used as one of the last lines of treatment. However, colistin-resistant ECC strains have emerged. The aim of this study was to prove that MgrB, the negative regulator of the PhoP/PhoQ two-component regulatory system, is involved in colistin resistance in ECC of cluster C-VIII, formerly referred to as Enterobacter hor-maechei subsp. steigerwaltii. An in vitro mutant (Eh22-Mut) was selected from a clinical isolate of Eh22. The sequencing analysis of its mgrB gene showed the presence of one nucleotide deletion leading to the formation of a truncated protein of six instead of 47 amino acids. The wild-type mgrB gene from Eh22 and that of a clinical strain of Klebsiella pneumoniae used as controls were cloned, and the corresponding recombinant plasmids were used for complementation assays. The results showed a fully restored susceptibility to colistin and confirmed for the first time that mgrB gene expression plays a key role in acquired resistance to colistin in ECC strains

Optimized hybrid nanospheres immobilizing Rhizomucor miehei lipase for chiral biotransformation

[EN] In this study, the immobilization of Rhizomucor miehei lipase into hybrid nanospheres containing a liposomal core was reported. Organic internal liposomal enzyme phase was protected by inorganic silica matrix, obtained with and without surfactant, that stabilizes the internal organic phase and isolates and protects the bioactive molecules. The optimized heterogeneous catalyst thus prepared was used for enantioselective esterification of (R,S)-ibuprofen. The influence of several catalytic parameters on the activity of hybrid nanospheres (type of solvent, nature of the alcohol, reaction temperature, etc.,) was investigated. The heterogeneous biocatalysts best performed at 37 degrees C, using isooctane as solvent and 1-propanol as alcohol (with ester yield ranging between 78 and 93%). High activity and stability (up to nine reaction cycles) of enzyme-immobilized hybrid nanospheres, with respect to the free form, were observed. R. miehei lipase, both in its free and immobilized forms, reacts only with the S(+) enantiomer of (R,S)-ibuprofen, in all the tested reaction conditions. (C) 2015 Elsevier Ltd. All rights reserved.The authors thank the financial support from Consolider-Ingenio MULTICAT CSD2009-00050, MAT2014-52085-C2-1-P, and Severo Ochoa Excellence Program SEV-2012-0267.Verri, F.; Díaz Morales, UM.; Macario, A.; Corma Canós, A.; Giordano, G. (2016). Optimized hybrid nanospheres immobilizing Rhizomucor miehei lipase for chiral biotransformation. Process Biochemistry. 51(2):240-248. https://doi.org/10.1016/j.procbio.2015.11.020S24024851

Growth hormone level at admission and its evolution during refeeding are predictive of short-term outcome in restrictive anorexia nervosa

International audienceThe growth hormone (GH)– insulin-like growth factor-1 (IGF-1) axis is dramatically altered in patients with anorexia nervosa (AN). The aim of the present study was to investigate whether GH and IGF-1 could be predictors of outcome in patients with a restrictive form of AN. Blood levels of GH, IGF-1, adipocytokines, ghrelin, insulin, glucose, and sex and thyroid hormones were measured in eleven women inpa-tients with AN and in ten healthy women controls. Three stages were compared during refeeding: admission (T0), when BMI reached 16 kg/m 2 (T1) and at discharge when BMI reached 17·5 kg/m 2 (T2). Clinical status was assessed 6 months after discharge from hospital (T3), and remission was defined by the maintenance of a BMI $ 17·5 kg/

First description of NDM-1-positive Klebsiella pneumoniae in the Tunisian community

First description of NDM-1-positive Klebsiella pneumoniae in the Tunisian community Sir, Multidrug-resistant bacteria, especially carbapenemase-producing Enterobacteriaceae, are a major public health-threat worldwide. As part of a collaborative monitoring programme, our laboratory at the University of Bordeaux has received a collection of multidrug-resistant bacterial strains to further characterise their β-lactamase content. They were sent from private Tunisian diagnostic laboratories and were collected from community patients suffering from urinary tract infection. In this context, multidrug-resistant isolate 18TA was collected in January 2018 in Sfax region from the urine of a 45-year old female with no previous hospitalisation during the preceding month and no history of recent foreign travel. Strain 18TA had been initially classified as Enterobacter spp. by biochemical tests (API 10S gallery). Following matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF/MS) (Bruker Daltonics) and confirmation by PCR amplification and sequencing of 16S rDNA, strain 18TA was re-identified as Klebsiella pneumoniae. Multilocus sequence typing (MLST) (http:// bigsdb.pasteur.fr/klebsiella/klebsiella.html) indicated that strain 18TA belonged to Sequence Type (ST), ST147. Minimum inhibitory concentrations (MICs) of various anti-microbials were determined using a BD Phoenix TM 100 automated system (BD Diagnostic Systems, Le Pont-de-Claix, France) and the results were interpreted using BD EpiCenter TM software (BD Diagnostic Systems). The MICs for ciprofloxacin and colistin were also determined by the broth microdilution method according to European Committee on Antimicrobial Susceptibility Testing 2019 guidelines (https://www.sfm-microbiologie.org/2019/05/06/ casfm-eucast-2019-v2/). Strain 18TA was resistant to all tested β-lactams, including carbapenems (Table 1). The strain was also resistant to gentamicin, tobramycin, quinolones (nalidixic acid), fluoroquinolones (cipro-floxacin) and trimethoprim/sulfamethoxazole (SXT) and showed decreased susceptibility to tigecycline (MIC = 2 mg/mL). It remained susceptible to amikacin, fosfomycin and colistin (Table 1). The imipenem/ethylene diamine tetra-acetic acid (EDTA) combined disk diffusion test was positive since the inhibition zone increased by 7 mm with the imipenem/EDTA disk compared with the imipenem disk alone, suggesting the presence of a metallo-β-lactamase (MBL) [1]. In addition, the double-disk synergy test (between amoxicillin/clavulanic acid and broad-spectrum cepha-losporins) showed the presence of an extended-spectrum β-lactamase (ESBL)-producing phenotype (data not shown). The transferability of the β-lactam resistance determinant was assessed by conjugation assay using an azide-resistant (Az R) mutant of Escherichia coli C600 as the recipient strain. Selection was performed on Mueller-Hinton agar plates supplemented with sodium azide (300 mg/mL) and ertapenem (4 mg/mL). A transfer frequency of ca. 10-4 transconjugants per donor was observed. Comparison of MICs between the transconjugant (Tc-18TA) and its recipient strain (C600 Az R) showed increased resistance not only to the tested β-lactams but also to gentamicin, tobramycin and SXT (Table 1). Total genomic DNA of strain 18TA was screened using different multiplex PCR amplifications for various β-lactamase genes (bla TEM-like , bla SHV-like , bla OXA-1-like , bla CTX-M groups 1, 2, 9, 18 and 25, bla OXA-48-like , bla KPC and bla GES and the MBL genes bla VIM , bla IMP and bla NDM) as described previously [2]. Amplification results following agarose gel electrophoresis analysis showed the presence of group 1 bla CTX-M and bla NDM genes together with bla TEM-like , bla SHV-like and bla OXA-1-like genes. Except for the bla SHV gene that was found in strain 18TA but not in the transconjugant Tc-18TA and that was attributed to the chromosomally-encoded species-specific enzyme of K. pneumoniae, the four other β-lactamases were also found in transconjugant Tc-18TA (Table 1). Amplification of the entire bla genes was performed and subsequent sequencing ((Custom DNA sequencing; Eurofins Genomics GmbH, Ebersberg, Germany) showed the presence of the narrow-spectrum β-lactamase genes bla TEM-1B and bla OXA-1 associated with the bla CTX-M-15 ESBL gene and the bla NDM-1 MBL gene both in 18TA and Tc-18TA (Table 1). Furthermore, amplifications searching for aac(3)-IIa (gentamicin and tobramycin resistance) and sul1 and dfrA1 (sulfamethoxazole and trimetho-prim resistance, respectively) were positive both in 18TA and Tc-18TA. These genes were also present in Kp3771, a ST147 NDM-1-producing K. pneumoniae strain recently recovered from a patient hospitalised in an intensive care unit of University Hospital Tahar Sfar in Tunisia [3]. NDM-1-positive K. pneumoniae strains have been previously described in Tunisia, but only from hospitalised patients [1-5]. The current study reports the first description of K. pneumoniae carrying the carbapenemase NDM-1 in the Tunisian community http://dx

Unacylated Ghrelin is associated with the isolated low HDL-cholesterol obese phenotype independently of insulin resistance and CRP level

<p>Abstract</p> <p>Background</p> <p>Low plasma high-density lipoprotein-cholesterol (HDL-c) level is commonly present in obesity and represents an independent cardiovascular risk factor. However, obese patients are a very heterogeneous population and the factors and mechanisms that contribute to low HDL-c remain unclear. The aim of this study was to investigate the association between plasma HDL-c levels and plasma hormonal profiles (insulin, adiponectin, resistin, leptin and ghrelin) in subsets of class II and III obese patients.</p> <p>Methods</p> <p>Fasting plasma levels of glucose, total cholesterol, LDL-c, HDL-c, triglycerides, free fatty acids, apoproteins A-I, B-100, B-48, C-II, C-III, insulin, hs-CRP, adipocytokines (adiponectin, resistin, leptin), unacylated ghrelin, body composition (DXA) and resting energy expenditure were measured in three subsets of obese patients: 17 metabolically abnormal obese (MAO) with metabolic syndrome and the typical metabolic dyslipidaemia, 21 metabolically healthy obese (MHO) without metabolic syndrome and with a normal lipid profile, and 21 isolated low HDL-c obese patients (LHO) without metabolic syndrome, compared to 21 healthy lean control subjects.</p> <p>Results</p> <p>Insulin resistance (HOMA-IR) increased gradually from MHO to LHO and from LHO to MAO patients (<it>p </it>< 0.05 between MHO and MAO and between LHO and MAO). In multiple regression analysis, serum unacylated ghrelin levels were only positively and independently associated with HDL-c levels in the LHO group (<it>p </it>= 0.032).</p> <p>Conclusions</p> <p>These results suggest that, in class II and III obese patients with an isolated low HDL-c phenotype, unacylated ghrelin is positively associated with HDL-c level independently of insulin resistance and CRP levels, and may contribute to the highly prevalent low HDL-c level seen in obesity.</p

The RNA Editing Pattern of cox2 mRNA Is Affected by Point Mutations in Plant Mitochondria

The mitochondrial transcriptome from land plants undergoes hundreds of specific C-to-U changes by RNA editing. These events are important since most of them occur in the coding region of mRNAs. One challenging question is to understand the mechanism of recognition of a selected C residue (editing sites) on the transcript. It has been reported that a short region surrounding the target C forms the cis-recognition elements, but individual residues on it do not play similar roles for the different editing sites. Here, we studied the role of the −1 and +1 nucleotide in wheat cox2 editing site recognition using an in organello approach. We found that four different recognition patterns can be distinguished: (a) +1 dependency, (b) −1 dependency, (c) +1/−1 dependency, and (d) no dependency on nearest neighbor residues. A striking observation was that whereas a 23 nt cis region is necessary for editing, some mutants affect the editing efficiency of unmodified distant sites. As a rule, mutations or pre-edited variants of the transcript have an impact on the complete set of editing targets. When some Cs were changed into Us, the remaining editing sites presented a higher efficiency of C-to-U conversion than in wild type mRNA. Our data suggest that the complex response observed for cox2 mRNA may be a consequence of the fate of the transcript during mitochondrial gene expression